1. Field of the Invention
The present invention relates to a tube; more particularly to a tube having multiple heat-dissipating paths.
2. Description of Related Art
By being environmental friendly and having low power consumption, the light-emitting diodes (LEDs) are gradually being used in lighting applications. For example, the LED tube has already been introduced to replace the conventional fluorescent lamp. The goal is to integrate the LEDs into everyday household and office lighting applications.
The LED tube is very temperature-sensitive. Generally speaking, the junction temperature (Tj) of an LED must be kept below 125 deg. Celsius to prevent malfunction. This criterion is essential to prevent the LED tube from malfunctioning. In addition, a temperature gradient usually exists along the tube shaft direction of the LED tube. This temperature gradient can cause the LEDs arranged along the tube to exhibit different lighting characteristics with respect to each other, which creates uneven illumination for the LED tube.
The increase in temperature for the LED tube is mainly due to the physical characteristics of the LED itself and the heat generated by the corresponding driving circuit. For example, the temperature of the LED chip would increase when the active layer of the LED chip is excited. Moreover, when in operation, the transformers and resistors of the driving circuit would generate heat as well. The increase in temperature can reduce the service life of the LED tube and cause failures. Also, the appearance of the temperature variation is existed along the tube shaft direction of the LED tube when the LED tube is in operation. This temperature variation is made worse due to the heat generated by the driving circuit. The temperature variation will cause uneven light distribution along the tube shaft direction of the LED tube, which negatively impacts the lighting performance.